Ultrahigh molecular weight polyalphaolefins especially higher olefins are extensively used as drag reducing polymers in pipelines. It is well known in the art that to synthesis ultrahigh molecular weight polyolefins, first and second generation i.e., traditional Ziegler-Natta catalysts are used. These catalyst systems are basically TiCl3 based and non supported in nature. The preferred catalyst system is TiCl3.1/3AlCl3 as catalyst and DEAC (diethyl aluminum chloride) as co-catalyst.
U.S. Pat. No. 4,358,572 teaches the usage of diether component to TiCl3.AlCl3 to provide better dispersion of the catalyst, reduces agglomeration of the catalyst and hence results in the improved activity of the catalyst.
U.S. Pat. No. 4,493,904 describes the usage of ketones and monoethers to the TiCl3.AlCl3.
U.S. Pat. No. 4,433,123 teaches the usage of phosphorus compounds along with the traditional ZN catalysts for polymerizing alpholefins to ultrahigh molecular weight.
U.S. Pat. No. 5,449,732 describes the usage of TiCl3.AA with dibutyl ether but in solvent free polymerization conditions.
U.S. Pat. No. 5,869,570 describes the usage of metallocene catalysts for polymerizing polyalphaolefins. They use viscosity reducing agent that includes a substantially hydrophobic dispersant which reduces the viscosity of the reaction mixture and disperse the localized micelles. They claim that the addition of the dispersant provides for high molecular weight polyalphaolefin and a more uniform molecular weight distribution of the resulting polyalphaolefin.
U.S. Pat. No. 5,442,019 and U.S. Pat. No. 5,416,179 describe the metallocene compounds, their preparation, suitable co-catalysts, and their use in polymerization processes.
EP1335941 describes Ziegler-Natta based catalyst system where magnesium dichloride supported catalyst is synthesized using monohydric alcohol and alkyl carboxylic acid esters as internal donor. The catalyst synthesized is further used for copolymerizing C4-C30 monoolefins with polyunsaturated aliphatic hydrocarbons like C4-C30 diene. This copolymerization is conducted using external donors based on alkoxy silanes and chain transferring agents such as hydrogen. The copolymerization is rapidly conducted to only 10-30% monomer conversions. The average molecular weight is >5 million Dalton. The said DRA obtain is a mixture of monomers, solvent and 7 wt % polymer.
None of the above said prior arts and the available literature discloses or teaches preparation of ultrahigh molecular weight polyalphaolefins using the supported ZN catalyst in the absence of internal electron donor with conversions >90%.